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本研究供试品种为先锋783，总叶数为19片，试验地为砂壤土，在全自动防雨棚下进行。通过调控喷水量，使正常供水的对照区土壤含水量接近田间持水量，干旱处理区于第14片叶伸出时停止供水18d。采用改良热平衡法连续监测玉米植株茎中汁液流速，直接确定整株蒸腾速率和冠层日蒸腾量。结果表明，当土壤含水量接近田间持水量时，植株蒸腾速率主要受制于太阳辐射等气象因子，并与蒸散势呈同步平行变化；当土壤含水量减少到正常水分含量的75％时，蒸腾速率迅速下降，不再反映气象因子的影响。与同步测定的叶片气孔传导率、叶卷曲指数及植株生长速率相比较，整株日蒸腾率能更准确地反映植株与土壤水分的关系。
The cultivars of this study were Pioneer 783 with total leaf number of 19, which was sandy loam soil under the fully automatic rain shelter. By controlling the amount of water spray, the soil moisture of the control area of normal water supply was close to the field capacity, and the water supply of the arid area was stopped for 18 days when the 14th leaf extended. The flow rate of juice in the stems of corn plants was continuously monitored by a modified heat balance method to directly determine the transpiration rate of the whole plant and the daily transpiration of the canopy. The results showed that the transpiration rate was mainly controlled by meteorological factors such as solar radiation when the soil water content approached the field water holding capacity and changed in parallel with the evapotranspiration potential. When the soil water content decreased to 75% of the normal moisture content, the transpiration rate Rapid decline, no longer reflect the impact of meteorological factors. Compared with the leaf stomatal conductance, leaf curl index and plant growth rate determined simultaneously, the transpiration rate of whole plant can more accurately reflect the relationship between plant and soil moisture.